1. Field of the Invention
The present invention relates to means for powering electrosurgical and electrocautery tools and instruments. More specifically, the present invention relates to cordless battery-powered means for generating power that are compact enough to fit within a handpiece, powerful enough for use in sealing and resecting operations in the lungs, and safe enough to provide risk reduction incentives over conventional generator systems. Most specifically, the present invention focuses on the aspects of the electrical circuitry design for the minigenerator system to provide increased energy efficiency, feedback and alert systems, and adjustable performance parameters to tailor the procedure to the needs of each patient.
2. Description of the Related Art
Battery-operated power generators are desirable for electrosurgical/electrocautery instruments because they eliminate the need for wires running from the instrument to generator boxes or wall outlets. This eliminates any chance of a leakage current fault that could harm the patient. That makes the unit inherently safe. In addition, safety compliance should be easy to obtain by sound electrical circuitry design that complies with well known and readily available industry standards (i.e. IEC 60601 and ISO 14971). With no wires, the surgeon would be free to articulate the unit without encumbrances, enabling more natural surgical techniques and a greater variety of techniques.
There have been other attempts to overcome the reliance upon electrical wires and cords in providing electrosurgical/electrocautery tools with a reliable power supply. These attempts have confronted the dilemma in that eliminating the wall outlet electrical power source and relying completely on battery power typically makes the instrument so bulky that it is no less awkward to use than instruments attached to wires. Alternatively, providing a smaller battery to make the instrument easier to handle may be okay for more refined smaller scale surgical work but current circuitry designs and modes of usage cannot provide the amount of power necessary for more intensive surgeries in larger organs. Accordingly, several designs have accepted wires as necessary for the supply of a sufficient amount of power. These designs have focused on alternatives that reduce the negative aspects of wires (i.e. the ability of wires to get in a surgeon's way) rather than eliminating them altogether. Examples follow.
U.S. Pat. No. 6,039,734 (hereinafter U.S. Pat. No. '734) entitled “Electrosurgical hand-held battery-operated instrument” by Colin Charles Owen Goble and assigned to Gyrus Medical Limited (Cardiff, GB) discloses an instrument that is truly without wires. However, it is noted that “[t]his instrument is primarily, but not exclusively, intended for fine surgical work, such as spinal, neurological, plastic, ear-nose-and-throat and dental surgery, and office procedures.” There is no mention of lung, pleural, chest, or thoracic capabilities. Additionally, the instrument uses a single treatment electrode and is monopolar (see Abstract, claim 1, 1:29-31, etc.). The array of surgical procedures compatible with such a design is limited. The minigenerator of the present invention can be used with bipolar instruments having multiple treatment electrodes and this expands the potential applications. Since the battery-operated instrument of U.S. Pat. No. '734 is monopolar it requires a return path to be built into the housing of the instrument in order to avoid localizing current in a patient's tissue in the region of a return pad. The return path takes the form of an electrically conductive shield outside the generator that provides capacitive coupling between the generator and its surroundings (see Abstract, claims 7-9, 1:38-43, etc.). This built-in return path adds some bulk to the device as the layering is: generator—insulator—conductive shield—insulator. This generator also uses and provides a conductive path of alternating current (AC) (see claim 18). The minigenerator of the present invention can also provide direct current (DC) for electrocautery in which current does not enter the patient's body. Direct current electrocautery may be safer in some situations.
U.S. Pat. No. 5,961,514 (hereinafter U.S. Pat. No. '514) entitled “Cordless electrosurgical instrument” by Gary L. Long, et al. and assigned to Ethicon Endo-Surgery, Inc. (Cincinnati, Ohio) achieves a “cordless” electrosurgical instrument in a narrow sense of the term in that the instrument itself is, in fact, cordless but for power it is required to screw-in or plug-in to a trocar adapter unit that has wires and is itself electrically charged by a wall outlet. The outside of the tubular instrument has electrical contacts that receive energy as the instrument is passed through a trocar cannula. Thus, the instrument must be passed through and in contact with the trocar cannula to receive energy and the trocar adapter unit has wires. Connecting the instrument to the trocar adapter provides an extra step and obligation for a surgeon to perform before beginning to operate. Requiring the instrument to pass through a trocar cannula limits the angles and directions in which an instrument can be manipulated to access and treat a target site since it has to pass through the wired trocar adapter first. Thus, the advances of this system, if any, seem marginal. Typical voltages coming from a wall electrical outlet are much higher than the maximum voltages of reasonably-sized batteries and passing such a high voltage through a trocar cannula adapter unit in proximity to the patient could be dangerous.
U.S. Pat. No. 6,569,163 (hereinafter U.S. Pat. No. '163) entitled “Wireless electrosurgical adapter unit and methods thereof” by Cary Hata, et al. and assigned to Quantumcor, Inc. (Irvine, Calif.) improves upon the wired trocar cannula adapter unit of U.S. Pat. No. '514 by providing an adapter unit that “contactably couples” to an energy source upon direct physical contact by the surgeon (4:30-38). “Contactable coupling” is defined in the patent as coupling two electrical contact elements by contacting without plugging or connection” (4:27-30). However, the system is not truly wireless in that wires exist, it is just that they are divided into separate discrete segments, hidden, and insulated. Wires extend through a surgeon's glove and/or gown to terminate in at least one electrically conductive patch zone (or two patch zones for bipolar instruments) that provides power to the adapter unit upon direct physical contact. A drawback of this system is that the instrument itself does not contactably couple to the power supply. Rather, the wireless adapter unit (WAU) stands between the electrical source in the surgeon's glove or gown and the electrosurgical instrument to be powered. The instrument itself actually connects to the WAU with a cable cord 25 and receptacle 24 (see FIG. 4) or it connects through wires stripped of their insulation and a spring-loaded plug (5:31-41). It seems it would be a better design to eliminate the adapter unit and contactably couple the electrical system in the surgeon's glove/gown directly with the instrument to be powered. This would streamline the connections and eliminate the duty to line-up and connect components in situ. This drawback is discussed and compared to the prior art (see 5:23-28, 5:31-41, and FIGS. 4A and 4B). U.S. Pat. No. '163 teaches away from a battery pack by suggesting the contactable coupling means described therein is superior because it doesn't take up space while batteries do and can make an instrument bulkier and heavier (2:7-14 and 4:36-38).
The minigenerator power system of the present invention overcomes the issues of all of these references by providing a truly wireless system that avoids both a separate adapter unit and the need for a coupling mechanism and is capable of being used with bipolar (in addition to monopolar) instruments. The elimination of a coupling mechanism reduces instrumentation set-up time and the on-site power generation source reduces charging or power-up time. The special handpiece is hermetically sealed, without any external wires, and with a modern battery having specially designed circuitry that minimizes power usage for a lighter, longer-lasting battery-powered instrument.